sedentary, horticultural tribes of the upper Missouri River went out into the Great Plains and became nomadic hunters after the introduction of the horse. The culture of the Navajos underwent profound change after they acquired herds of sheep and a market for their rugs was developed. The older theories of simple environmentalism, some of which maintained that even styles of myths and tales were determined by topography, climate, flora, and other factors, are no longer in vogue. The present view is that the environment permits, at times encourages, and also prohibits the acquisition or use of certain cultural traits but otherwise does not determine culture change. The Fuegians living at the southern tip of South America, as viewed by Charles Darwin on his voyage on the Beagle, lived in a very cold, harsh environment but were virtually without both clothing and dwellings. Diffusion"Culture is contagious," as a prominent anthropologist once remarked, meaning that customs, beliefs, tools, techniques, folktales, ornaments, and so on may diffuse from one people or region to another. To be sure, a culture trait must offer some advantage, some utility or pleasure, to be sought and accepted by a people. (Some anthropologists have assumed that basic features of social structure, such as clan organization, may diffuse, but a sounder view holds that these features involving the organic structure of the society must be developed within societies themselves.) The degree of isolation of a sociocultural system--brought about by physical barriers such as deserts, mountain ranges, and bodies of water--has, of course, an important bearing upon the ease or difficulty of diffusion. Within the limits of desirability on the one hand and the possibility of communication on the other, diffusion of culture has taken place everywhere and in all times. Archaeological evidence shows that amber from the Baltic region diffused to the Mediterranean coast; and, conve...
